Question

I only would like to call

Process.Start("notepad.exe");

when the service starts; But it doesn’t work at all. No notepad is called right after I chose to start the service in the windows service manager.

Thank you a lot.

[UPDATE]

I made it work after putting a check mark in logon tab to allow interactive desktop. But I don’t know what does this really mean ? How can I schedule to run a task on any computer if it always asks me to accept to view the message in the Interactive Desktop Detection panel ?

Answer 1

A Windows service is different from a standard process and by default it can’t interact with the user desktop(this is a rule of the Windows OS), so to launch a process and allow it to interact with the user desktop you have to flag the Interact with desktop option …

Bear in mind that starting from Windows Vista services are running under session 0 and every time that the service try to start the process a panel is shown to the user the let the user choose if he wants to run the process or not; to overcome this limitation (panel that ask for confirmation) the only way is to launch the process from the service directly with the CreateProcessAsUser function of the Windows API …

Take a look at this function that i have developed some times ago, that make use of the CreateProcessAsUser API, and start a process from a service without asking anything even in Vista/7:

    /// <summary>
    /// LaunchProcess As User Overloaded for Window Mode 
    /// </summary>
    /// <param name="cmdLine"></param>
    /// <param name="token"></param>
    /// <param name="envBlock"></param>
    /// <param name="WindowMode"></param>
    /// <returns></returns>
    private static bool LaunchProcessAsUser(string cmdLine, IntPtr token, IntPtr envBlock,uint WindowMode)
    {
        bool result = false;

        PROCESS_INFORMATION pi = new PROCESS_INFORMATION();
        SECURITY_ATTRIBUTES saProcess = new SECURITY_ATTRIBUTES();
        SECURITY_ATTRIBUTES saThread = new SECURITY_ATTRIBUTES();
        saProcess.nLength = (uint)Marshal.SizeOf(saProcess);
        saThread.nLength = (uint)Marshal.SizeOf(saThread);

        STARTUPINFO si = new STARTUPINFO();
        si.cb = (uint)Marshal.SizeOf(si);

        //if this member is NULL, the new process inherits the desktop
        //and window station of its parent process. If this member is
        //an empty string, the process does not inherit the desktop and
        //window station of its parent process; instead, the system
        //determines if a new desktop and window station need to be created.
        //If the impersonated user already has a desktop, the system uses the
        //existing desktop.

        si.lpDesktop = @"WinSta0\Default"; //Default Vista/7 Desktop Session
        si.dwFlags = STARTF_USESHOWWINDOW | STARTF_FORCEONFEEDBACK;

        //Check the Startup Mode of the Process 
        if (WindowMode == 1)
            si.wShowWindow = SW_SHOW;
        else if (WindowMode == 2)
        { //Do Nothing
        }
        else if (WindowMode == 3)
            si.wShowWindow = 0; //Hide Window 
        else if (WindowMode == 4)
            si.wShowWindow = 3; //Maximize Window
        else if (WindowMode == 5)
            si.wShowWindow = 6; //Minimize Window
        else
            si.wShowWindow = SW_SHOW;


        //Set other si properties as required.
        result = CreateProcessAsUser(
        token,
        null,
        cmdLine,
        ref saProcess,
        ref saThread,
        false,
        CREATE_UNICODE_ENVIRONMENT,
        envBlock,
        null,
        ref si,
        out pi);

        if (result == false)
        {
            int error = Marshal.GetLastWin32Error();
            string message = String.Format("CreateProcessAsUser Error: {0}", error);
            Debug.WriteLine(message);

        }

        return result;
    }